This tweet from Sergey Galyonkin, marketing director at 1C Multimedia and this blog post have sparked rumors that S.T.A.L.K.E.R. 2 is in development at Bethesda Softworks after development of the first-person shooter sequel was frozen following trouble at developer GSC Game World. The Steam Forums (thanks PlayStation Universe) has a translation:

The following info is from a reliable source but isn't official, keep that in mind.

Sergey Grigorovich didn't sell the brand name "STALKER".

Bethesda is going to publish a STALKER game and has all the rights to it.

The game is multiplatform(consoles+PC) and is based on Bethesda technology.

It's being made by a studio familiar with that technology(possibly Obisidian or the Fallout 3 team from Bethesda, but no facts as of yet). It is almost 100% guaranteed that it's not a Ukrainian studio.

Bethesda will be able to buy the brand name from Grigorovich later, but for now all the misc. merchandise is his responsibility.